JP2745635B2 - Brake actuator with lining wear compensation device - Google Patents

Abstract

PURPOSE:To eliminate movement defects caused by inclination of a piston and deformation of a guide pin by providing an auxiliary piston behind a main cylinder of a brake actuator and by pulling back a main piston to the original position by the auxiliary piston. CONSTITUTION:An auxiliary piston 6 and an auxiliary piston 7 to be stored in it are provided behind a main cylinder 2 for storing a brake piston 1. Moreover, an output axis 7a of the auxiliary piston 7 is made to airtightly penetrate the main cylinder 2 and to be connected to the brake piston 1. An introducing port 8 for fluid pressure for operating the auxiliary piston 7 backwardly is provided at the auxiliary cylinder 6. When fluid pressure is introduced into the auxiliary cylinder 6, backward thrust is generated in the auxiliary piston 7, and the brake piston 1 is pulled back to the original position by this force. In this way, movement defects caused by inclination of the piston and deformation of a guide pin can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a brake actuator with a built-in mechanical lining wear compensation device that presses and slides a brake lining against a disk or a tread surface of a wheel for braking a vehicle or the like. About. More specifically, it is an actuator that facilitates a reset operation when replacing a lining.

[Conventional technology]

2. Description of the Related Art Among known brake actuators employed in disk brakes and the like, there are known brake actuators having a built-in lining wear compensation device as shown in FIG.

The compensating device 5 shown in the figure is provided with a coiling bush 5b in which a guide pin 5a is fixed to the shaft center of a cylinder 2 accommodating the brake piston 1 and an appropriate sliding resistance (resistance exceeding the force of a spring 5e) is obtained on the pin. It is fitted. A bush housing 5c having one end fixed to the bush 5b and the other end fixed to the piston 1 is provided between the housing and a seat plate 5d which is fixed to the piston 1 with a play in the piston axial direction of t. The return spring 5e of the piston 1 is interposed between them.

By doing so, the brake piston 1 becomes t + α
(Α = abrasion amount of the lining at the time of the current braking) When moving forward, the seat plate 5d comes into contact with the bush 5b at the stroke exhaust position of t, and then the bush 5b is slid forward α on the guide pin 5a. In the forward position, the bush 5b restricts the rearward movement of the piston 1 when depressurizing. Therefore, the amount of return of the piston due to the restoring force of the spring 5e is always limited to t, and the return to the cylinder 2 due to the lining wear is reduced. A change in the working fluid supply amount and a response delay are prevented. Reference numeral 3 denotes a friction pad that is pressed against the piston 1, and D denotes a brake disk.

[Problems to be solved by the invention]

In a brake actuator in which a return point upon release of braking gradually advances in accordance with lining wear, it is necessary to push the piston 1 back to the initial position when the life pad is replaced.

However, a brake actuator with a built-in wear compensator requires a large push-back force as compared to an actuator without the compensator because a large sliding resistance acts extra between the guide pin and the coiling bush.
When the force is eccentrically applied to the piston 1, a trouble such as bending of the guide pin or inclination of the piston and difficulty in movement is likely to occur. Therefore, in order to avoid this trouble, it is necessary to proceed with caution using a special push-back tool or jig, and it takes time to reset.

Also, since careful work using special tools and jigs is required, it is difficult to work in a narrow place.

An object of the present invention is to provide a brake actuator that is effective in solving such a problem.

[Means for solving the problem]

A brake actuator with a lining wear compensation device according to the present invention is provided with a sub-cylinder and a sub-piston to be stored in the back of a main cylinder that stores a brake piston, and further has an output shaft of the sub-piston airtightly penetrated into the main cylinder. In addition to the connection to the brake piston, the auxiliary cylinder is provided with a fluid pressure inlet for operating the auxiliary piston backward.

The structure of the actuator can be simplified by using the guide pin and the output shaft of the auxiliary piston.

[Action]

When a fluid pressure such as compressed air is introduced into the sub cylinder, a reverse thrust is generated in the sub piston, and the brake piston is returned to the original position by this force. Therefore, the resetting work only needs to supply a fluid pressure by connecting a hose or the like to the fluid pressure introduction port of the sub cylinder, and there is no problem even in a narrow place.

Also, the thrust of the sub piston is transmitted to the brake piston via the output shaft guided by the partition between the main and sub cylinders, so that the brake piston is pulled straight and bent by the guide pins of the wear compensator. Eccentric load is not applied.

〔Example〕

 FIG. 1 shows an embodiment of the present invention.

As shown in the figure, a brake piston 1 whose outer periphery is sealed by a seal ring 4 is inserted into a cylinder 2 opened toward a tread surface a of a wheel W. A sub-cylinder 6 is provided in series behind the cylinder 2, and a sub-piston 7 having an output shaft 7a is inserted therein. Numeral 8 is a fluid pressure inlet provided in each of the cylinders 2 and 6, to which a working fluid pressure source for the brake is connected. On the other hand, the inlet 8 of the sub-cylinder 6 may be screwed with a nipple to close the inlet of the nipple with a rubber stopper or the like so that air can be released except when required. Reference numeral 3 'denotes a brake shoe which is brought into sliding contact with the tread surface a.
Are connected by

In addition, the output shaft 7a is air-tightly penetrated into the cylinder 2 and the tip is connected to the piston 1. The lining wear compensator 5 is provided with a coiling bush 5b on the output shaft 7a.
And a bush housing 5c, and a housing 5c received on a seat plate 5d between the cylinders 2 and 6, and a partition wall for receiving the housing at a stroke exhaust position of t in the axial direction of the piston.
10, a return spring 5e is interposed. That is, in this example, the output shaft 7a is also used as the guide pin 5a in FIG.
A relative movement corresponding to the lining wear amount is caused between the output shaft 7a that moves + α and the coiling bush 5b whose movement amount is limited to t.

In the actuator configured as described above, the auxiliary piston 7 is at the front end position of the stroke when the shoe 3 'has reached the end of its life. Therefore, when a fluid pressure such as air is introduced into the cylinder 6, a backward thrust is generated in the sub piston 7, and both pistons 7 and 1 return to their original positions by the force.

〔effect〕

As described above, in the brake actuator of the present invention, since the hydraulically operated auxiliary piston is provided behind the main cylinder and the main piston is returned to the original position by the auxiliary piston, the piston moves straight, Troubles such as poor movement due to the inclination of the piston and deformation of the guide pin do not occur.

In addition, since resetting is possible only by connecting an air hose or the like, special tools and jigs become unnecessary, and
Even in a narrow place, work can be performed quickly without any trouble.

The actuator according to the present invention can be used for a floating type and a piston opposed type disk brake, as well as a brake for bringing a friction material into sliding contact with a tread surface of a vehicle. In any case, the replacement of the friction material can be simplified. , Can effectively contribute to reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the actuator of the present invention, and FIG. 2 is a sectional view showing an example of a conventional actuator. DESCRIPTION OF SYMBOLS 1 ... Brake piston, 2 ... Cylinder, 3 '... Brake shoe 5 ... Lining wear compensation device 6 ... Sub cylinder, 7 ... Sub piston, 7a ... Output shaft, 8 ... Inlet, 9 ... ... connecting pins, 10 ... partition walls.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-242140 (JP, A) JP-B 32-5210 (JP, B1) JP-B-30-2761 (JP, B1)

Claims (2)

(57) [Claims] A member mounted on a guide pin in the axial direction of the piston with a sliding resistance of not less than a predetermined value is slipped by a forward force of a brake piston by an amount corresponding to a lining wear amount during braking, and the member returns when depressurized. In a brake actuator that limits the return amount of a brake piston by a spring, a sub-cylinder and a sub-piston are provided behind the main cylinder that stores the brake piston, and the output shaft of the sub-piston is hermetically sealed in the main cylinder. A brake actuator with a lining wear compensation device, characterized in that the brake cylinder is provided with a fluid pressure inlet for operating the sub-piston rearward, while being connected to the brake piston by penetrating the sub-cylinder. 2. A brake actuator with a lining wear compensation device according to claim 1, wherein said guide pin also serves as an output shaft of said auxiliary piston.